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为了研究层流预混火焰中二甲醚的氧化分解路径,利用同步辐射真空紫外光电离及分子束取样质谱技术,测量了二甲醚浓燃火焰主要物种及主要中间物种的摩尔分数空间分布曲线。基于典型的二甲醚燃烧化学反应机理和CHEMKIN化学反应动力学模拟软件,对相同条件的一维平面火焰进行了数值模拟,结合试验及数值模拟结果对二甲醚的氧化分解路径进行了分析。研究结果表明:甲醛和甲基是二甲醚燃烧过程中最主要的C1中间物种,乙烯和乙炔是主要C2中间物种;浓燃条件下,二甲醚主要通过脱氢反应消耗,使二甲醚产生脱氢反应的最主要的原子是H,其次是OH、CH3和O;二甲醚的脱氢产物甲氧基甲基极不稳定,在火焰中一经生成马上就被消耗掉,试验中没有观测到它的存在;CH2O脱氢生成HCO,HCO脱氢生成CO,CO再被OH氧化成CO2;反应CO+OHCO2+H是火焰后期生成CO2的主要方式。
In order to study the oxidative decomposition path of DME in laminar premixed flame, the spatial distribution curve of the mole fraction of DME and its main intermediate species was measured by synchrotron radiation vacuum ultraviolet photoionization and molecular beam sampling mass spectrometry . Based on the typical DME chemical reaction mechanism and CHEMKIN chemical reaction kinetics simulation software, the one-dimensional planar flame of the same condition was numerically simulated. The oxidation and decomposition path of DME was analyzed based on the experiment and numerical simulation results. The results show that formaldehyde and methyl are the most important intermediate species of C1 during the combustion of dimethyl ether, while ethylene and acetylene are the main intermediates of C2. Under concentrated combustion conditions, dimethyl ether is consumed mainly by dehydrogenation, The most important atom to produce the dehydrogenation reaction is H, followed by OH, CH3 and O. The dehydrogenation product methoxymethyl of dimethyl ether is extremely unstable and is consumed as soon as it is generated in the flame. In the experiment, The existence of CH 2 O was observed. The dehydrogenation of CH 2 O to HCO led to the dehydrogenation of HCO to CO, which was further oxidized to CO 2 by CO 2. The reaction CO + OH CO 2 + H was the main mode of post-combustion CO2 generation.